Communication Product Updates

Compiled by Zac Ellis of FHWA's Office of Research and Technology Services

Below are brief descriptions of products recently published online by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. Some of the publications also may be available from the National Technical Information Service (NTIS). In some cases, limited copies are available from the Research and Technology (R&T) Product Distribution Center.

When ordering from NTIS, include the NTIS publication number (PB number) and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:

Traffic microsimulation models are becoming widely used and valuable tools for modeling existing and planned transportation networks and conditions. These models can help transportation professionals make important decisions on such topics as new roadway alignments and configurations, new interchange configurations and locations, the addition of auxiliary lanes on freeways, strategies and plans to manage work zones, strategies and plans for operations and intelligent transportation systems, coordination and timing of traffic signals, and the addition of high-occupancy toll lanes. Although many of the microsimulation models used today provide a wide range of analysis options, some gaps and limitations still exist that can affect the accuracy of their results. As described in this factsheet, the Next Generation SIMulation (NGSIM) program-a public-private partnership between FHWA, commercial microsimulation software developers, and the academic research community-aims to enable reliable and valid transportation decisions through improved traffic simulation modeling. FHWA will act as a market facilitator and use focused public resources to influence and stimulate the commercial simulation market by fostering an environment for public-private coordination.

For more information, visit the NGSIM Web site at http://ngsim.fhwa.dot.gov.

Freeway Lane Selection Algorithm: NGSIM Factsheet

Publication No. FHWA-HRT-06-136

At the heart of the NGSIM program is the development of freely available algorithms for driver behavior that represent the fundamental logic within traffic simulation models. A comprehensive survey of NGSIM stakeholder groups, coupled with an assessment of existing microsimulation systems and driver behavior algorithms, revealed a number of high-priority needs for algorithm development under the NGSIM program. As a result, one of the first algorithms researchers developed under the NGSIM program is the Freeway Lane Selection algorithm, which is the topic of this factsheet.

For more information, visit the NGSIM Web site at http://ngsim.fhwa.dot.gov.

To support development of microscopic driver behavior algorithms, the NGSIM program is collecting detailed, high-quality datasets on traffic flow. NGSIM stakeholder groups identified collection of real-world data on vehicle trajectories as important to understanding and researching microscopic driver behavior. The NGSIM datasets represent the most detailed and accurate field data collected to date for research and development related to traffic microsimulation. The dataset for Interstate 80 in the San Francisco, CA, area, which was the first of several datasets collected under the NGSIM program, is the topic of this factsheet.

For more information, visit the NGSIM Web site at http://ngsim.fhwa.dot.gov.

The objective of this study was to expand and improve a rapid method for assessing channel stability that was developed previously by P.A. Johnson, G. Gleason, and R.D. Hey. The study includes additional factors, such as major physiographic units across the United States, a greater range of bank materials and complexities, critical bank heights, stream types and processes, streams with sandy beds, and inchannel bars or a lack of bars. Another goal of the study was to tailor R.C. Thorne's reconnaissance method for bridge inspection and stability assessment needs. Researchers observed stream-bridge intersections across the United States to develop and test the stability assessment method. The researchers conducted site visits at 57 stream-bridge intersections in 14 physiographic regions and subregions.

Data collected in the report include the locations and global positioning system coordinates of the bridges, the physiographic province, land use, stream classification, bed and bar material, percentage of sand in the bed material, controls in the banks or on the bed, bank vegetation, bank material, bank height, and any erosion-related characteristics. The researchers also described any variability in stream types and common characteristics within each of the physiographic regions. They identified thirteen indicators for the stability assessment method and assigned a rating of poor, fair, good, or excellent for each indicator. The researchers obtained an overall rank by summing the 13 ratings. To address the sensitivities of various stream types to the indicators and rankings, they determined the appropriate ranges of rankings for three categories of stream channels. Each of the 57 stream-bridge intersections also was described in terms of lateral and vertical stability. Finally, the report presents a simplified version of Thorne's field sheets for stream reconnaissance and collecting data for the stability assessment. The field sheets provide a record of the conditions during each visit.

Researchers conducted a review of literature and standard guidance to assess the current state of knowledge and practice regarding curing hydraulic-cement concrete. Based on this information, they developed a draft guide for curing hydraulic-cement concrete pavements. The draft guidance was based on the type of curing used (water added, water retention by sheet, or curing compound) and the temperature effects.

The researchers conducted laboratory studies on topics for which information was needed but not currently available. The investigation resulted in a set of guidelines that focused particularly on moisture retention and temperature immediately after placing (initial curing period) and details related to selecting materials for the final curing. The report also covers test methods for evaluating the application rate of the curing compound and the effectiveness of curing. A separate report, Guide for Curing of Portland Cement Concrete Pavements, Volume I (FHWA-RD-02-099), captures the details of the recommended guidance. That report is intended to be the principal medium for technology transfer.

The NTIS order number for Volume II is PB2007-100064.

Traffic Analysis Toolbox Volume I: Traffic Analysis Tools Primer

Publication No. FHWA-HRT-04-038

This primer provides an overview of traffic analysis tools in the transportation analysis process. The document defines different categories of traffic analysis tools and describes the challenges and limitations of using them. The authors compare analyses based on the Highway Capacity Manual with traffic simulation-based analyses and describe the criteria for selecting the appropriate type of traffic analysis tool. An appendix provides a list of tools within each category and their corresponding Web sites.

This is the first in a series of volumes in the Traffic Analysis Toolbox. The other volumes are Traffic Analysis Toolbox Volume II: Decision Support Methodology for Selecting Traffic Analysis Tools (FHWA-HRT-04-039) and Traffic Analysis Toolbox Volume III: Guidelines for Applying Traffic Microsimulation Modeling Software (FHWA-HRT-04-040).

This report provides an overview of the role of traffic analysis tools and offers a detailed decision-support methodology for selecting the appropriate tool for the job at hand. The authors describe a set of criteria for selecting the appropriate tool and score each category of tools according to its relevance to those criteria. The criteria include the analysis context, study area, facility type, travel mode, management strategy, traveler response, performance measures, and cost-effectiveness. Analysts can rate the tool categories for a particular transportation analysis task using processes and worksheets in the report based on the analyst's weighting of the criteria. In addition, the report highlights some challenges and limitations of using traffic analysis tools.

The report includes the following appendixes: a summary of current limitations to the Highway Capacity Manual methodologies, worksheets for tool category selection, worksheets for selecting an individual tool within a category, a list of resources for further reading, and a list of traffic analysis tools by category.

This report provides a guideline for using traffic microsimulation software in transportation analyses. The report highlights a seven-step process for microsimulation analysis from project start to completion. The steps are as follows: (1) scope the project, (2) collect data, (3) develop a base model, (4) check for errors, (5) compare model measures of effectiveness to field data (and adjust model parameters), (6) analyze alternatives, and (7) prepare the final report. The report describes each step in detail and provides an example problem applying the process.